Analysis of information sources in references of the Wikipedia article "Operation Horseshoe" in English language version.
the Serbian police began clearing ... people [who] were marched down to the station and deported... the UNCHR registered 848,000 people who had either been forcibly expelled or had fled
By the time the Serbian Army and government withdrew from Kosovo, between 848,000 and 863,000 ethnic Albanians had been expelled from Kosovo and up to 590,000 had become internally displaced.
All told, government forces expelled 862,979 ethnic Albanians from Kosovo, and several hundred thousand more were internally displaced, in addition to those displaced prior to March 1999. More than 80 percent of the entire population of Kosovo-90 percent of Kosovar Albanians-were displaced from their homes.
Est. Number of Kosovar Albanians expelled from Kosovo by Serbs, March to June 1999: 863,000